1. Technical Field
This invention relates generally to an imaging system for verifying light reflection spectrum from a sample object, and more specifically to an imaging system using a monochromatic image capture device and a plurality of colored light sources to verify that the color of an object is within a specified range.
2. Background Art
Modern electronic devices often come in complex mechanical housings constructed from multiple parts. By way of example, many commonly available portable video cameras now include LCD screens that flip, rotate, and twist away from the housing. Doors pop open to accept discs and memory cards, and detachable lights, microphones, and remote control devices snap to and from the camera. Similarly, many mobile telephones are available with “flip” housings that open like a clamshell. Each half of the clamshell may include multiple parts, such as housing bottoms, housing tops, sides, doors, latches, windows, and so forth.
Each part used in the assembly of the electronic device is generally manufactured in batches that are separate from the others. For instance, a group of doors may be made from one batch of plastic. A group of housing bottoms may then be manufactured from metal and painted. The components are then brought together and assembled on a manufacturing line to form the finished product.
A problem associated with the manufacture of multi-part devices is that of matching color. End users expect the colors of the various housing parts to match. If, for example, a metal housing that has been painted is a slightly different shade of red than the plastic door attaching to it, the overall appearance of the device can be compromised.
Prior art solutions for color matching, including those described in U.S. Pat. No. 5,593,990, require a technician to compare—with the human eye—multiple parts to a standard swatch. If the part or sample “looks” the same as the swatch to the technician, the sample is passed. If it looks different, it fails.
The problem with this prior art solution is that it is based on the human eye, which is unique to the individual. A quality control technician in China will not have the same eye as one in South America. Consequently, when a manufacturing process is global, components of differing hues may ship as the same stock color. Worse, devices may ship with mismatching parts.
There is thus a need for an improved method of spectrum verification.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.